Burette float and drainage aperture

ABSTRACT

The present invention relates to a turbulence minimization apparatus comprising a float and seat assembly adapted to control turbulence and formation of microbubbles in a quantity of contrast media in the burette of a contrast media delivery system. The float includes an upper convex surface providing an impact surface for droplets of contrast media which fall from the inlet of the burette, a lower convex surface for sealing a drainage bore when the volume of contrast media has been substantially drained from the burette, and a predetermined amount of buoyancy. The seat assembly includes a plurality of fluid passageways that allow contrast media to contact the lower convex surface of the float allowing the buoyancy of the float to separate the float from the drainage bore when there is more than a predetermined amount of fluid in the drip chamber.

BACKGROUND OF THE INVENTION

1. The Field of the Invention

The present invention relates to contrast media delivery systems. In more particular, the present invention relates to a burette float and seat for use with a contrast media delivery system.

2. The Relevant Technology

Patient fluid delivery systems have long been used in medicine to ensure reliable and safe delivery of fluids to patients. Typically, such delivery systems include a source of fluid such as an infusate bag or bottle, a patient access apparatus such as a catheter or trocar, and delivery tubing for conveying the fluid from the source of fluid to the patient. Some delivery systems also incorporate a burette at one or more positions in the delivery tubing. A burette typically comprises a clear cylindrical apparatus having a drip chamber of a larger diameter than the delivery tubing. The drip chamber of the burette is configured to be partially filled with fluid while fluid is flowing to the burette. The drip chamber of the burette helps eliminate any potential air bubbles in the delivery line. Air bubbles in the delivery line are dissipated as the fluid enters the burette and forms droplets. The reservoir also minimizes air bubbles that can form in the outlet line of the burette as a result of interruption of flow of fluid into the burette.

When the fluid in the fluid source is exhausted, fluid is no longer delivered to the burette from the inlet tubing. Because fluid is no longer delivered to the burette, the fluid level in the burette begins to lower. This allows the practitioner to observe the fluid level in the burette to ascertain whether a replacement fluid source is needed without actually observing the fluid level in the fluid source. As long as the volume of fluid in the burette exceeds a certain threshold, fluid continues to be delivered to the patient from the outlet of the burette. As a result, the burette provides an amount of time in which fluid continues to be delivered to the patient after the fluid source has been depleted. This allows the practitioner to replace the fluid source without interrupting the delivery of fluid to the patient.

One problem that has been encountered with the use of burettes relates to filling of the drip chamber of the burette. Typically as the drip chamber is filled, fluid flowing into the drip chamber from the inlet of the burette does not immediately contact the volume of fluid in the drip chamber because the drip chamber is only partially filled with fluid. Instead, the fluid forms droplets which fall from the burette inlet onto the surface of the fluid volume in the drip chamber. In some circumstances, when the droplets hit the fluid volume the velocity of the droplets may create turbulence or microbubbles in the volume of fluid. The formation of microbubbles may be undesirable in some circumstances where they may be delivered to the vasculature of the patient.

The formation of microbubbles can be particularly challenging where the fluid being delivered to the patient comprises contrast media. Contrast media is utilized to allow imaging equipment such as X-ray or MRI to view the flow of fluids in the patient's vasculature or other body systems. Contrast media includes radioactive or isotopic qualities that permit the contrast media to be detected by the imaging equipment. The types of materials that are often utilized in contrast media often have molecular weight and/or a high viscosity. The high viscosity can increase the number and size of microbubbles while inhibiting the migration of the microbubbles out of the volume of contrast media.

A variety of mechanisms have been developed to minimize the formation of microbubbles. One mechanism comprises a ball or other spherical member that is configured to float in the volume of fluid in the burette. The size and buoyancy of the ball is configured such that the droplets strike the surface of the ball instead of the surface of the volume of fluid. This not only slows the velocity of the droplets, but also provides a surface along which the droplets can flow and enter the volume of fluid.

FIG. 1 illustrates a prior art burette 1 having a float 12 for use with a volume of contrast media 19. In the illustrated embodiment, float 12 includes buoyant qualities that permit float 12 to be suspended in contrast media 19 such that a portion of float 12 is positioned above the surface of contrast media 19. By being suspended such that a portion of float 12 is above the surface of contrast media 19, float 12 provides an impact surface for droplets entering burette 1. For reasons that will be explained hereinafter, float 12 is not illustrated floating such that a portion of float 12 is above the surface of the contrast media 19.

In the illustrated embodiment, burette 1 includes a drip chamber 10, float 12, seat 14, outlet 16, and inlet 18. Drip chamber 10 provides a reservoir for holding the volume of contrast media 19 in burette 1. Contrast media flows from the contrast media delivery source through inlet 18, into drip chamber 10, and then exits the burette through outlet 16. Typically, the contrast media flowing into drip chamber 10 from inlet 18 forms droplets. Float 12 is configured to provide an impact surface for the droplets which prevents direct impact of the droplets on the surface of the volume of contrast media 19.

When contrast media no longer flows into drip chamber 10 from inlet 18, the level of contrast media 19 in drip chamber 10 begins to lower. When the level of contrast media 19 lowers sufficiently, float 12 contacts seat 14. Seat 14 is formed from the inner surface of the wall of drip chamber 10. Seat 14 is configured to conform to the shape of float 12 to provide an air tight seal with float 12. By providing an air tight seal between seat 14 and float 12, a vacuum effect is created in outlet 16 and downstream from burette 1. The vacuum effect stops the flow of fluid to the patient and prevents air from entering into the delivery line downstream from burette 1. By preventing air from entering into the delivery line downstream from burette 1, the practitioner need not remove air from the delivery line before resuming the flow of fluids to the patient. This allows for smooth and efficient replacement of the fluid source allowing the flow of fluid to the patient to resume once the fluid level in drip chamber 10 of burette 1 is returned to normal levels.

One problem that is presented by the configuration of float 12 and seat 14 relates to the air tight seal created by float 12 and seat 14 and the vacuum effect downstream from float 12 and seat 14. The air tight seal and vacuum effect discourages separation of float 12 from seat 14 as drip chamber 10 begins to refill with liquid. This can be exacerbated by the fact that seat 14 is formed from the inner wall of drip chamber 10. Because seat 14 is formed from the inner wall of drip chamber 10, the contact between seat 14 and float 12 is along much of the bottom surface of float 12 making it difficult for contrast media to flow to the underside of float 12. Because the buoyancy of float 12 results from contact between contrast media 19 and the underside of float 12, insufficient buoyancy is created to overcome the vacuum effect which prevents separation of float 12 and seat 14. Additionally, most or all of the contrast media 19 is primarily in contact with the upper surface of float 12 resulting in a downward pressure being exerted on float 12 by contrast media 19. The downward force exerted by contrast media 19 on the upper surface of float 12 also prevents separation between float 12 and seat 14.

While float 12 remains in air tight contact with seat 14, flow of contrast media 19 to the patient will not resume. To overcome the vacuum effect and air tight seal between float 12 and seat 14 and in an attempt to resume flow of contrast media 19 to the patient, practitioners may shake or tap burette 1 in an attempt to dislodge float 12. By dislodging float 12, contrast media 19 can move to the underside of float 12 allowing the buoyancy of float 12 to separate from seat 14 and float to the surface of contrast media 19. However, shaking or tapping of burette 1 can result in the additional turbulence in contrast media 19. The turbulence can create the type of microbubbles which float 12 was originally designed to prevent. Additionally, during the time in which the float 12 is covered with a volume of contrast media 19, droplets falling from inlet 18 can also create microbubbles in the volume of contrast media 19.

BRIEF SUMMARY OF THE INVENTION

The present invention relates to a turbulence minimization apparatus for use with a burette of a contrast media delivery system. The turbulence minimization apparatus is adapted to control turbulence and formation of microbubbles in a quantity of contrast media in the burette. In one embodiment of the present invention the turbulence minimization apparatus comprises a float and a seat assembly. The float includes an upper convex surface and a lower convex surface. The float also has a predetermined amount of buoyancy adapted to facilitate separation of the float from the seat assembly when there is more than a predetermined amount of contrast media in the drip chamber of the burette.

The seat assembly includes a drainage bore and a seat. The seat includes a plurality of fluid passageways that allow contrast media to flow beneath the float and contact the lower convex surface of the float. In one embodiment, the seat with the plurality of fluid passageways comprises a plurality of projections. The space between the projections comprises the fluid passageways. The projections are configured to accommodate the float such that the float is positioned over the drainage bore creating an air tight seal with the drainage bore when the volume of contrast media in the burette falls below a predetermined level. In this manner the float minimizes the introduction of air into the line downstream from the burette. The projections also allow the contrast media to flow to the underside of at least a portion of the float such that when the level of the contrast media reaches a predetermined level, the buoyancy of the float overcomes any potential vacuum effect separating the float from the drainage bore.

According to one embodiment of the present invention the float is formed from first and second convex members that form an air cavity when combined. According to another embodiment of the present invention, the float includes an upper convex surface and a lower non-convex surface. According to another embodiment of the present invention, the seat assembly includes a drainage bore and a seat member. According to one embodiment of the present invention, the seat member allows contrast media to flow to the underside of at least a portion of the float such that when the level of the contrast media reaches a predetermined level, the buoyancy of the float overcomes any potential vacuum effect between the drainage bore and the float. In one embodiment the seat member comprises a plurality of projections that support the float while allowing contrast media to contact the lower surface of the float. In another embodiment, the fluid passageways comprise channels, voids, or apertures that allow contrast media to contact the underside of the float.

These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

To further clarify the above and other advantages and features of the present invention, a more particular description of the invention will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. It is appreciated that these drawings depict only typical embodiments of the invention and are therefore not to be considered limiting of its scope. The invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:

FIG. 1 is a prior art depiction of a burette of a contrast media delivery system having a float.

FIG. 2 illustrates a turbulence minimization apparatus having a float and seat assembly for use with a burette according to one exemplary embodiment of the present invention.

FIG. 3 is a perspective view of the float and seat assembly of FIG. 2.

FIG. 4 is a partial cross-sectional view of the float and seat assembly of FIG. 2.

FIG. 5 is a front cut-away view of the burette of FIG. 2 illustrating the float positioned on the seat assembly when the level of contrast media is below a predetermined level.

FIG. 6 is a front cut-away view of the burette illustrating the manner in which the seat assembly allows contrast media to flow to the lower surface of the float.

DETAILED DESCRIPTION

The present invention relates to a turbulence minimization apparatus for use with a burette of a contrast media delivery system. The turbulence minimization apparatus is adapted to control turbulence and formation of microbubbles in a quantity of contrast media in the burette. In one embodiment of the present invention the turbulence minimization apparatus comprises a float and a seat assembly. The float includes an upper convex surface and a lower convex surface. The float also has a predetermined amount of buoyancy adapted to facilitate separation of the float from the seat assembly when there is more than a predetermined amount of contrast media in the drip chamber of the burette.

The seat assembly includes a drainage bore and a seat. The seat includes a plurality of fluid passageways that allow contrast media to flow beneath the float and contact the lower convex surface of the float. In one embodiment, the seat comprises a plurality of projections. The space between the projections comprises the fluid passageways of the seat. The projections are configured to accommodate the float such that the float is positioned over the drainage bore creating an air tight seal with the drainage bore when the volume of contrast media in the burette falls below a predetermined level. In this manner the float minimizes the introduction of air into the line downstream from the burette. The projections also allow the contrast media to flow to the underside of at least a portion of the float such that when the level of the contrast media reaches a predetermined level, the buoyancy of the float overcomes any potential vacuum effect allowing the float to separate from the drainage bore.

According to one embodiment of the present invention the float is formed from first and second convex members that form an air cavity when combined. According to another embodiment of the present invention, the float includes an upper convex surface and a lower non-convex surface. According to another embodiment of the present invention, the seat assembly includes a drainage bore and a seat member. According to one embodiment of the present invention, the seat member allows contrast media to flow to the underside of at least a portion of the float such that when the level of the contrast media reaches a predetermined level, the buoyancy of the float overcomes any potential vacuum effect between the drainage bore and the float. In one embodiment the seat member comprises a plurality of projections that support the float while allowing contrast media to contact the lower surface of the float. In another embodiment, the fluid passageways comprise channels, voids, or apertures that allow contrast media to contact the underside of the float. According to another embodiment, the curved configuration of the lower surface of the float minimizes the entrapment of air in the chamber that could otherwise be released into the outlet of burette and eventually the delivery line.

FIG. 2 illustrates a turbulence minimization apparatus 118 utilized in connection with burette 100 of a contrast media delivery system. Turbulence minimization apparatus 118 controls turbulence and the formation of microbubbles in a quantity of contrast media 112 in burette 100 of the contrast media delivery system. In the illustrated embodiment, turbulence minimization apparatus 118 comprises a float 120 and a seat assembly 140. Float 120 provides a contact surface for droplets falling from an inlet 110 of burette 100. Seat assembly 140 allows contrast media to flow to the underside of at least a portion of float 120 such that when the level of the contrast media reaches a predetermined level, the buoyancy of float 120 overcomes any potential vacuum effect downstream from float 120. This allows the buoyancy of float 120 to create separation between float 120 and seat assembly 140 when there is more than a predetermined amount of contrast media in the burette 100. Turbulence minimization apparatus 118 is one example of a valve assembly.

In the illustrated embodiment, burette 100 includes a drip chamber 106, an outlet 108, and an inlet 110. Drip chamber 106 is configured to hold a volume of contrast media 112. According to one embodiment of the present invention, a drip chamber wall 104 is comprised of a transparent or semi-transparent material which allows the user to view the level of contrast media 112 in drip chamber 106. Drip chamber wall 104 defines the size and configuration of drip chamber 106. Drip chamber 106 comprises the interior lumen of barrel 102 in which contrast media 112 is positioned. In the illustrated embodiment, drip chamber 106 is substantially cylindrical along the length of barrel 102.

Outlet 108 is positioned at the bottom of burette 100 in fluid communication with outlet line 114. Inlet 110 is positioned at the top of burette 100 in fluid communication with inlet line 116. In the illustrated embodiment, contrast media flows from the contrast media source, such as a bag or bottle, into inlet line 116. From inlet line 116 the contrast media flows into drip chamber 106 through inlet 110. Typically, as the contrast media enters drip chamber 106 from inlet 110, it forms droplets that fall from inlet 110 into drip chamber 106.

Float 120 is positioned in drip chamber 106. Float 120 includes a predetermined amount of buoyancy which positions the upper surface of float 120 above the surface of the volume of contrast media 112. Float 120 provides an impact surface for the droplets of contrast media falling from inlet 110. As the droplets of contrast media strike float 120, the velocity of the droplets is substantially reduced. The droplets can then flow along the upper surface of float 120 and into the volume of contrast media 112. In the illustrated embodiment, the diameter of float 120 is sufficiently smaller than the diameter of drip chamber 106 to allow unobstructed flow of contrast media from the upper surface of float 120 into the volume of contrast media 112. Additionally, the curved configuration of the lower surface of the float 120 minimizes the entrapment of air in the chamber 10 that could otherwise be released into the outlet 108 of burette and eventually the outlet line 114.

The volume of contrast media 112 in drip chamber 106 flows into a drainage bore of seat assembly 140, through outlet 108, and into outlet line 114. From outlet line 114 the contrast media can be infused into the patient. When the volume of contrast media in the contrast media source is exhausted, contrast media no longer flows into drip chamber 106 from inlet 110. Where contrast media from the contrast media source is no longer filling drip chamber 106, as long as the volume of contrast media 112 continues to flow into outlet line 114, the level of the volume of contrast media 112 will begin to lower. As the level of the volume of contrast media 112 begins to lower, the positioning of float 120 also begins to lower. In this manner, float 120 can be utilized as an indicator of the level of the volume of contrast media 112 in drip chamber 106. The lowering of float 120 signals to the practitioner that the source of contrast media is exhausted and needs to be replaced. The volume of contrast media 112 in drip chamber 106 maintains the flow of contrast media to the patient even where the contrast media source is exhausted and contrast media is no longer filling burette 100. This provides the practitioner with time to replace the source of contrast media after the contrast media is no longer flowing into burette 100.

When the volume of contrast media 112 in drip chamber 106 is substantially emptied from drip chamber 106, float 120 contacts and is supported by seat assembly 140. The configuration of the lower surface of float 120 conforms to the configuration of the upper surface of seat assembly 140 such that seat assembly 140 accommodates and provides a desired positioning of float 120. In the illustrated embodiment, the lower surface of float 120 comprises a convex surface while the upper surface of seat assembly 140 comprises a concave surface. The lower surface of float 120 is configured to provide an air tight seal with the drainage bore of the seat assembly. The configuration of float 120 and seat assembly 140 will be discussed in greater detail with reference to FIGS. 3-6.

As will be appreciated by those skilled in the art, a variety of types and configurations of turbulence minimization apparatuses can be utilized with a variety of types and configurations of burettes without departing from the scope and spirit of the present invention. For example, in one embodiment a burette that is non-cylindrical in configuration is utilized. In another embodiment, at least one of the upper or lower surfaces of the float is substantially convex in configuration. In yet another embodiment, a secondary assembly such as a diffusion plate that controls movement of droplets of contrast media is utilized. In another embodiment, the turbulence minimization apparatus is utilized with a fluid delivery system other than a contrast media delivery system.

FIG. 3 is a close-up perspective view of float 120 and seat assembly 140 of turbulence minimization apparatus 118. In the illustrated embodiment, float 120 comprises an upper convex surface 124, an outer circumferential rim 126, a lower convex surface 134, and an outer circumferential rim 136. Upper convex surface 124 provides a contact surface for droplets of contrast media falling from inlet 110 of burette 100 (see FIG. 2). Lower convex surface 134 is positioned on float 120 opposite upper convex surface 124. Lower convex surface 134 is configured to contact an upper surface of seat assembly 140.

Outer circumferential rim 126 is positioned adjacent upper convex surface 124. Outer circumferential rim 136 is positioned adjacent lower convex surface 134. Outer circumferential rim 126 is coupled to outer circumferential rim 136. Outer circumferential rim 126 and outer circumferential rim 136 provide a desired amount of displacement between upper convex surface 124 and lower convex surface 134. In the illustrated embodiment, the degree of curvature of upper convex surface 124 and lower convex surface 134 and the amount of displacement provided by outer circumferential rim 126 and outer circumferential rim 136 results in a disk-like configuration of float 120.

The disk-like configuration of float 120 minimizes flipping of float 120 which would otherwise position upper convex surface 124 below the surface of the volume of contrast media 112. In the illustrated embodiment, the curvature of upper convex surface 124 is similar to the curvature of the lower convex surface 134. This allows both the upper convex surface 124 and lower convex surface 134 to perform similarly regardless of the orientation of float 120 in the event that float 120 is flipped upside down. The disk-like configuration of float 120 also provides a greater surface area of both the upper convex surface 124 and lower convex surface 134 relative to the overall volume of float 120. The surface area of upper convex surface 124 provides a greater contact area for falling droplets. The surface area and degree of curvature of lower convex surface 134 increases the buoyancy of float 120 relative to the overall volume of float 120.

In the illustrated embodiment, float 120 is formed from a deformable material that allows lower convex surface 134 of float 120 to conform to the surface of a circumferential contact surface 146 of drainage bore 142 to create a fluid tight seal with a drainage bore of seat assembly 140. As will be appreciated by those skilled in the art, float 120 can be constructed utilizing a number of materials without departing from the scope and spirit of the present invention. For example, in one embodiment the float is constructed from a soft and pliable material such as silicone or urethane which has a shore hardness of between 20 A and 40 A and is coated with a parylene or other surface treatment. In another embodiment, the float is constructed from a material selected from rubberized foam, neoprene, isoprene, thermoplastics, elastomeric plastics, rubbers, or other materials having a desired amount of buoyancy either alone, in combination with air pockets, or in combination with other buoyant materials. As will be appreciated by those skilled in the art, materials having varying shore hardness outside of the range of 20 A and 40 A and different material properties from the above referenced materials can also be utilized. Additionally, the seat can be adapted to have soft and pliable properties to accommodate floats having more rigid material properties.

As will be appreciated by those skilled in the art, a variety of types and configurations of floats can be utilized without departing from the scope and spirit of the present invention. For example, in one embodiment the outer circumferential rims provide a greater displacement between the upper convex surface and the lower convex surface. In another embodiment, one or both of the upper and lower convex surfaces have a greater or lesser degree of curvature. In yet another embodiment, one or both of the upper and lower surfaces are non-convex in configuration. In another embodiment, the lower convex surface of the float is coated with a pliable material to facilitate the fluid tight seal with the drainage bore of the seat assembly.

In the illustrated embodiment, seat assembly 140 includes a drainage bore 142 and a seat 150. Drainage bore 142 provides a conduit for the volume of contrast media flowing from drip chamber 106 of burette 100 (see FIG. 2). Drainage bore 142 is positioned in fluid communication with outlet 108 of burette 100 (see FIG. 2). Drainage bore 142 is positioned at the center of seat assembly 140. Drainage bore 142 includes a wall 144 and a circumferential contact surface 146. Wall 144 comprises the outer boundary of drainage bore 142. Wall 144 extends the length of drainage bore 142 from the bottom of the burette to the top of circumferential contact surface 146. Circumferential contact surface 146 is positioned at the top of wall 144. Circumferential contact surface 146 is configured to provide an airtight seal when positioned in contact with float 120.

Seat 150 is configured to accommodate the lower convex surface 134 of float 120. In the illustrated embodiment, seat 150 includes a plurality of projections 152 a-h. The plurality of projections 152 a-h provide a desired amount of displacement between the bottom of the burette and the lower convex surface 134 of float 120. Additionally, projections 152 a-h properly position float 120 relative to circumferential contact surface 146 to provide an air tight seal between float 120 and circumferential contact surface 146.

Projections 152 a-h include contact surfaces 154 a-h. Contact surfaces 154 a-h collectively form an upper contact surface of seat 150. In the illustrated embodiment, contact surfaces 154 a-h form a concave surface for accommodating lower convex surface 134 of float 120. The portions of contact surfaces 154 a-h adjacent circumferential contact surface 146 of drainage bore 142 are at substantially the same elevation of circumferential contact surface 146. As a result, when lower convex surface 134 of float 120 is in contact with contact surfaces 154 a-h of projections 152 a-h, lower convex surface 134 contacts the entire circumference of circumferential contact surface 146 providing an air tight seal between circumferential contact surface 146 and lower convex surface 134.

The configuration of projections 152 a-h allows the contrast media to flow between projections 152 a-h and into contact with lower convex surface 134 of float 120. In the illustrated embodiment, the spaces between projections 152 a-h comprise fluid passageways that allow the contrast media to contact the lower convex surface 134 of float 120. As a result, where the contrast media begins to fill the chamber of the burette, the contrast media contacts and provides a buoyant force on lower convex surface 134 of float 120. In the illustrated embodiment, the buoyancy of float 120 is selected to be greater than the force vector exerted on float 120 resulting from the combination of the vacuum effect in drainage bore 142 and the force vector resulting from any fluid positioned above float 120. When the level of the contrast media is raised sufficiently, the amount of buoyancy of float 120 exceeds any vacuum effect between lower convex surface 134 and circumferential contact surface 146. As a result, lower convex surface 134 separates from circumferential contact surface 146 and the flow of fluid through drainage bore 142 to the outlet of the burette can resume.

As will be appreciated by those skilled in the art, a variety of types and configurations of seat assemblies can be utilized without departing from the scope and spirit of the present invention. For example, a variety of types, numbers, and configurations of projections of the seat can be utilized. In one embodiment, a circumferential member is attached to the outer edges at the top of the projections. In another embodiment, the seat of the seat assembly comprises a concave surface with a plurality of fluid passageways, voids, channels, or apertures for allowing contact between the contrast media and the lower convex surface of the float. In another embodiment, the drainage bore does not include a wall and the circumferential contact surface is positioned at the same elevation as the bottom of the chamber of the burette. In another embodiment, the projections of the seat extend from the drip chamber wall rather from the bottom of the burette.

FIG. 4 is a cut-away view of float 120 and seat assembly 140 according to one embodiment of the present invention. In the illustrated embodiment, float 120 comprises an upper portion 122, an air cavity 130, and a lower portion 132. Upper portion 122 is coupled to lower portion 132 to form air cavity 130. Upper portion 122 includes an upper convex surface 124, an outer circumferential rim 126, and an upper column member 128. Upper convex surface 124 provides an impact surface for droplets of contrast media falling from the inlet of the burette. Outer circumferential rim 126 provides a mechanism for coupling upper portion 122 to lower portion 132. Upper column member 128 provides internal structural support for the center of upper portion 122. Upper column member 128 also provides a coupling mechanism for securing upper portion 122 to lower portion 132.

Lower portion 132 includes a lower convex surface 134, an outer circumferential rim 136, and a lower column member 138. Lower convex surface 134 is configured to be accommodated by seat 150 of seat assembly 140 when there is less than a predetermined amount of contrast media in the drip chamber. Outer circumferential rim 136 provides a mechanism for coupling lower portion 132 to upper portion 122. Lower column member 138 provides internal structural support for the center of lower portion 132. Lower column member 138 also provides a coupling mechanism for securing upper portion 122 to lower portion 132.

As will be appreciated by those skilled in the art, a variety of types and configurations of floats can be utilized without departing from the scope and spirit of the present invention. For example, in one embodiment, the buoyancy of the float is provided by the buoyancy of the materials from which the float is constructed. In another embodiment, the upper portion and lower portion are sufficiently rigid to obviate the need for one or more column members. In yet another embodiment, the float is formed from a single uniform piece of material.

In the illustrated embodiment a cut-away view of seat assembly 140 is shown. It can be seen that the configuration of wall 144 extends drainage bore 142 to the top of circumferential contact surface 146. The configuration of circumferential contact surface 146 and the contact surfaces (see i.e. 154 a, e) of the projections (see i.e. 152 a, e) provides a fluid tight seal between circumferential contact surface 146 and lower convex surface 134 when float 120 is positioned on seat 150.

FIG. 5 is a cut-away side view of burette 100 illustrating the juxtaposition of float 120 relative to seat assembly 140 when the volume of contrast media has been drained from drip chamber 106 of burette 100. In the illustrated embodiment, lower convex surface 134 of float 120 is positioned in contact with the contact surfaces (see e.g. 154 a) of the projections (see e.g. 152 a) of seat 150. As previously discussed, when lower convex surface 134 is in contact with seat 150, lower convex surface 134 forms an air tight seal with circumferential contact surface 146 (see FIG. 4). The air tight seal between lower convex surface 134 and circumferential contact surface 146 (see FIG. 4) and the siphon effect of contrast media 112 in outlet 108 and outlet line 114 creates a vacuum effect in outlet 108 and outlet line 114 (see also FIG. 4). The vacuum effect in outlet 108 and outlet line 114 prevents additional flow of the remaining volume of contrast media 112 from outlet line 114 to the patient. This prevents migration of air into outlet line 114 when the volume of contrast media in drip chamber 106 in burette 100 is exhausted. By preventing migration of air into outlet line 114, the practitioner need not remove air that would otherwise form in outlet line 114 when the volume of contrast media in drip chamber 106 is returned to normal levels.

FIG. 6 is a cut-away side view of burette 100 illustrating the juxtaposition of float 120 relative to seat assembly 140 when contrast media is again introduced into drip chamber 106 of burette 100. In the illustrated embodiment, contrast media flows from inlet line 116 into drip chamber 106 through inlet 110. As the contrast media flows into drip chamber 106 it forms droplets which fall onto upper convex surface 124 of float 120. Once the droplets strike upper convex surface 124 of float 120, the droplets of contrast media flow from the upper convex surface 124 of float 120 into the volume of contrast media in drip chamber 106.

As the volume of contrast media in drip chamber 106 increases, the configuration of the projections (see e.g. 152 a) and the fluid pathways created by the projections allows contrast media to flow beneath and into contact with at least a portion of lower convex surface 134 of float 120. As the volume of contrast media continues to increase, the buoyancy of float 120 overcomes any vacuum effect maintaining the contact between float 120 and seat assembly 140. As a result, float 120 separates from seat assembly 140 resuming the flow of contrast media from drainage bore 142 (see FIG. 4), through outlet 108, outlet line 114, and into the patient.

As will be appreciated by those skilled in the art, a variety of types and configurations of turbulence minimization apparatuses can be utilized without departing from the scope and spirit of the present invention. For example, in one embodiment the degree of curvature of the lower convex surface and the configuration of the seat positions the drainage bore at the level of the bottom of the burette. In another embodiment, the lower surface of the float is concave while the upper surface of the seat is convex in configuration. In another embodiment, the float includes a lower relief surface which allows the contrast media to contact a portion of the lower surface of the float.

The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is, therefore, indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope. 

1. A valve assembly for use with a burette of a fluid delivery system, the burette having an inlet for providing the inflow of contrast media to the burette, a drip chamber for containing a volume of contrast media and a volume of air for permitting dissipation of air bubbles in the contrast media entering the drip chamber from tubing upstream from the burette, and an outlet for allowing passage of the volume of contrast media from the drip chamber to portions of the fluid delivery system downstream from the burrette, the valve assembly comprising; a float positioned in the drip chamber of the burette, the float having an upper surface, a lower surface, and a predetermined amount of buoyancy, the float being adapted to provide an impact surface for droplets of fluid passing from the inlet into the drip chamber while permitting the passage of fluid from the upper surface of the float to the lower surface of the float; and a seat configured to accommodate and provide support for the float when there is less than a predetermined amount of contrast media in the drip chamber, the seat and float forming an air tight seal between the drip chamber and the outlet of the burette to prevent the passage of air into the outlet of the burette when there is less than a predetermined amount of fluid in the drip chamber, wherein the seat includes one or more fluid passageways providing access to the lower surface of the float such that the fluid in the drip chamber can contact a sufficient portion of the lower surface of the float to allow the buoyancy of the float to cause separation between the float and the seat when there is more than a predetermined amount of fluid in the drip chamber to allow the fluid to flow from the drip chamber into the outlet of the burette.
 2. The float and seat assembly of claim 1, wherein the seat comprises a plurality of projections.
 3. The float and seat assembly of claim 2, wherein the plurality of fluid passageways are positioned between the plurality of projections.
 4. The float and seat assembly of claim 3, wherein the contrast media flows through the fluid passageways between the plurality of projections to contact the lower surface of the float.
 5. The float and seat assembly of claim 1, wherein the lower surface of the float is comprised of a material that has a predetermined amount of deformability.
 6. The float and seat assembly of claim 5, wherein the deformability of the material comprising the lower convex surface of the float is configured to conform to the seat to provide an air tight seal with the seat.
 7. The float and seat assembly of claim 1, wherein the lower surface of the float has a relief that conforms to the relief of an upper contact surface of the seat.
 8. The float and seat assembly of claim 7, wherein the seat includes a drainage bore positioned between the drip chamber and the outlet of the burette.
 9. The float and seat assembly of claim 8, wherein the seat is configured to position the float in a level manner such that the lower surface of the float contacts a circumferential contact surface of the drainage bore in an air tight manner.
 10. The float and seat assembly of claim 1, wherein the lower surface of the float has a substantially convex configuration.
 11. The float and seat assembly of claim 10, wherein the seat forms a concave contact surface to support the substantially convex configuration of the float.
 12. A turbulence minimization apparatus for use with a burette of a contrast media delivery system, the burette including an inlet, a drip chamber, and an outlet, the turbulence minimization apparatus adapted to control turbulence and the formation of microbubbles in a quantity of contrast media in the drip chamber, the turbulence minimization apparatus comprising: a float positioned in the drip chamber of the burette, the float having an upper convex surface, a lower convex surface, and a predetermined amount of buoyancy; and a seat configured to accommodate and provide a concave support surface for the lower convex surface of the float when there is less than a predetermined amount of contrast media in the drip chamber, the seat and float forming a fluid tight seal between the drip chamber and the outlet of the burette to prevent the passage of air into the outlet of the burette when there is less than a predetermined amount of fluid in the drip chamber, wherein the seat includes one or more fluid passageways providing access to the lower surface of the float such that the fluid in the drip chamber can contact a substantial portion of the lower surface of the float to allow the buoyancy of the float to overcome the vacuum effect between the float and the seat when there is more than a predetermined amount of fluid in the drip chamber to allow the fluid to flow from the drip chamber into the outlet of the burette.
 13. The turbulence minimization apparatus of claim 12, wherein the upper convex surface provides an impact surface for droplets falling from the inlet of the burette.
 14. The turbulence minimization apparatus of claim 13, wherein the seat comprises a plurality of projections.
 15. The turbulence minimization apparatus of claim 14, wherein each of the plurality of projections include a contact surface configured to accommodate and support the lower convex surface of the float.
 16. The turbulence minimization apparatus of claim 15, wherein the contact surfaces of the plurality of projections collectively comprise the concave support surface of the seat.
 17. The turbulence minimization apparatus of claim 16, wherein the seat includes a drainage bore having a circumferential contact surface configured to contact the lower convex surface of the float.
 18. The turbulence minimization apparatus of claim 17, wherein the circumferential contact surface and the lower convex surface of the float form an air tight seal for preventing air from entering into the drainage bore when the contrast media in the drip chamber is substantially drained from the burette.
 19. The turbulence minimization apparatus of claim 17, wherein the circumferential contact surface is positioned at substantially the same level as the inner portion of the plurality of projections immediately adjacent the circumferential contact surface.
 20. A turbulence minimization apparatus adapted to control turbulence and the formation of microbubbles in a quantity of contrast media in a chamber of a burette of a contrast media delivery system, the turbulence minimization apparatus being configured to seal an outlet of the burette when the volume of contrast media in the chamber of the burette falls below a predetermined level to minimize the introduction of air into a delivery line of the contrast media delivery system downstream from the outlet of the burette, the turbulence minimization apparatus comprising: a float positioned in the chamber of the burette, the float having an upper surface, a lower surface, and a predetermined amount of buoyancy; and a seat assembly configured to be positioned on the bottom of the burette in fluid connection with the outlet of the burette, the seat assembly comprising: a drainage bore positioned in the center of the seat assembly, the drainage bore being in fluid connection with the outlet of the burette; and a seat having an upper surface configured to accommodate the lower convex surface of the float, wherein the seat includes a plurality of fluid passageways configured to allow the contrast media to contact at least a portion of the lower convex surface of the float, and wherein the lower convex surface of the float provides a fluid tight seal with the drainage bore when the lower convex surface of the seat is in position with the upper surface of the seat.
 21. The turbulence minimization apparatus of claim 20, wherein the fluid passageways comprise a plurality of apertures.
 22. The turbulence minimization apparatus of claim 20, wherein the apertures are formed through the upper surface of the seat forming a conduit from beneath the seat to the lower surface of the float.
 23. The turbulence minimization apparatus of claim 20, wherein the fluid passageways comprise channels.
 24. The turbulence minimization apparatus of claim 23, wherein the channels are formed along the upper surface of the seat.
 25. The turbulence minimization apparatus of claim 20, wherein the seat comprises a plurality of projections and the fluid passageways comprise the spaces between the projections.
 26. The turbulence minimization apparatus of claim 20, wherein the lower surface of the float comprises a lower convex surface and the upper surface of the seat comprises an upper concave surface which mirrors the lower convex surface of the float.
 27. The turbulence minimization apparatus of claim 20, wherein the lower surface of the float comprises a lower concave surface and the upper surface of the seat comprises an upper convex surface which mirrors the lower concave surface of the float.
 28. The turbulence minimization apparatus of claim 20, wherein the lower surface of the float is substantially convex in configuration.
 29. The turbulence minimization apparatus of claim 20, wherein the buoyancy of the float results from the material from which the float is comprised
 30. The turbulence minimization apparatus of claim 20, wherein the buoyancy of the float results from an air cavity positioned between the upper surface and lower surface of the float.
 31. The turbulence minimization apparatus of claim 20, wherein the buoyancy of the float results from a combination of an air cavity internal to the float and the material from which the float is comprised. 